2016-12-23T18:52:10

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BackgroundPleistocene glaciations had considerable impact on phylogeographic patterns within and among closely related species of many vertebrates. Compared to Europe and North America, research on the phylogeography of vertebrates in East Asia, particularly in China, remains limited. The black-spotted frog (Pelophylax nigromaculata) is a widespread species in East Asia. The wide distribution of this species in China makes it an ideal model for the study of palaeoclimatic effects on vertebrates in East Asia. Our previous studies of P. nigromaculata revealed significant subdivisions between the northeast China populations and populations in other regions of the mainland. In the present study, we aim to see whether the deepest splits among lineages and perhaps subsequent genealogical divisions are temporally consistent with a Pleistocene origin and whether clade geographic distributions, with insight into expansion patterns, are similarly spatially consistent with this model.ResultsUsing 1143 nucleotides of the mitochondrial cytochrome b gene from 262 individuals sampled from 28 localities, two main clades (clade A and clade B) differing by c. 7.72% sequence divergence were defined from parsimony analyses. The corresponding timing of lineage divergence, 0.92 Mya, indicates a most likely Pleistocene split. The A clade is further subdivided into two sub-clades, A1 and A2 with 1.22% sequence divergence. Nested clade phylogeographical and population demographic analyses suggested that the current distribution of this frog species was the result of range expansion from two independent refugia during the last interglacial period. We discovered a population within which haplotype lineages A and B of P. nigromaculata coexist in the Dongliao area of China by nucleotide sequences, PCR-RFLP and ISSR (inter simple sequence repeat) patterns. The ISSR result in particular supported divergence between the mitochondrial clades A and B and implied introgressive gene flow between the two divergent lineages.ConclusionNested clade phylogeographical and population demographic analyses indicate that the current distribution of P. nigromaculata is the result of range expansion from two independent refugia during the last interglacial period in late Pleistocene. One refugium was in east China and the lower elevations of south-western plateau. The distribution of the other mitochondrial clade is consistent with the presence of a refugium in the Korean Peninsula. The gene flow as detected by ISSR markers suggests a range expansion of the two refugia and a secondary contact between the two highly divergent lineages in the Dongliao (DL) area of northeast China.

A phylogeny of gekkotan lizards was derived from C-mos nuclear DNA sequence data. Forty-one currently recognized genera, representing all major gekkotan lineages, were included in the study. A total of 378 bp of partial C-mos gene sequences was obtained and aligned. Maximum parsimony (MP) and maximum likelihood (ML) trees were generated based on unweighted analysis using PAUP*; similar tree topologies were recovered by both methods. The Eublepharidae were monophyletic and its relationship to other major clades was poorly resolved. The Pygopodidae of Kluge (1987) was monophyletic, but relationships within this group differed from those retrieved by previous analyses. The Diplodactylini + padded carphodactylines were the sister group of pygopods + padless carphodactylines. The Gekkonidae were monophyletic, but we found no evidence in support of the Teratoscincinae, as Teratoscincus was embedded well within the gekkonids. Both MP and ML analyses supported the basal position of Sphaerodactylus within the gekkonids, in contrast to morphologically based hypotheses. We propose a new higher order classification of the Gekkota that reflect these results. Five gekkotan families: Eublepharidae, Gekkonidae, Pygopodidae, Diplodactylidae, and Carphodactylidae are recognized. The higher order status of the sphaerodactyls will require more intensive sampling of this group. Our results support the hypothesis that the early cladogenesis of the Gekkota was associated with the split of Eastern Gondwanaland from Western Gondwanaland. Divergences among living genera in the Eublepharidae and the Eastern Gondwanan lineages (Diplodactylidae, Pygopodidae and Carphodactylidae) may be older than those in the Gekkonidae.

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